Helleborus plant named ‘BLT04’

ABSTRACT

A new and distinct cultivar of  Helleborus  plant named ‘BLT04’, characterized by its compact, upright and mounded plant habit; strong and vigorous growth habit; leaflets with distinctive venation; freely flowering habit; single pink-colored flowers; and good garden performance.

Botanical designation: Helleborus niger×Helleborus sternii. Cultivar denomination: ‘BLT04’.

BACKGROUND OF THE INVENTION

The present invention relates to a new and distinct cultivar of Helleborus plant, botanically known as Helleborus niger×Helleborus sternii, and hereinafter referred to by the name ‘BLT04’.

The new Helleborus is a product of a planned breeding program in Hampshire, United Kingdom. The objective of the breeding program was to create new frost-tolerant Helleborus cultivars with unique and attractive flower coloration.

The new Helleborus plant originated from a cross-pollination in Hampshire, United Kingdom in 2000, of Helleborus niger ‘Louis Cobbet’, not patented, as the female, or seed, parent with a proprietary selection of Helleborus sternii, not patented, as the male, or pollen, parent. The new Helleborus plant was discovered and selected by the Inventor as a single flowering plant from within the progeny of the stated cross-pollination grown in a controlled environment in Hampshire, United Kingdom in 2000.

Asexual reproduction of the new Helleborus plant by tissue culture in a controlled environment in The Netherlands since 2000, has shown that the unique features of this new Helleborus plant are stable and reproduced true to type in successive generations.

SUMMARY OF THE INVENTION

Plants of the new Helleborus have not been observed under all possible environmental conditions. The phenotype may vary somewhat with variations in environment and cultural practices such as temperature and light intensity without, however, any variance in genotype.

The following traits have been repeatedly observed and are determined to be the unique characteristics of ‘BLT04’. These characteristics in combination distinguish ‘BLT04’ as a new and distinct cultivar of Helleborus:

-   -   1. Compact, upright and mounded plant habit.     -   2. Strong and vigorous growth habit.     -   3. Leaflets with distinctive venation.     -   4. Freely flowering habit.     -   5. Single pink-colored flowers.     -   6. Good garden performance.

Plants of the new Helleborus can be compared to plants of the male parent selection. Plants of the new Helleborus are more freely flowering than plants of the male parent selection.

Plants of the new Helleborus can be compared to plants of the female parent, ‘Louis Cobbet’. Plants of the new Helleborus have larger flowers than plants of ‘Louis Cobbet’.

Plants of the new Helleborus can be compared to plants of Helleborus niger×Helleborus sternii ‘HGC Silvermoon’, disclosed in U.S. Plant Pat. No. 15,639. Plants of the new Helleborus differ primarily from plants of ‘HGC Silvermoon’ in the following characteristics:

-   -   1. Plants of the new Helleborus have larger and lighter-colored         leaves than plants of ‘HGC Silvermoon’.     -   2. Plants of the new Helleborus are more freely flowering than         plants of ‘HGC Silvermoon’.     -   3. Plants of the new Helleborus and ‘HGC Silvermoon’ differ in         flower color as plants of ‘HGC Silvermoon’ have white to light         green-colored flowers.

BRIEF DESCRIPTION OF THE PHOTOGRAPH

The accompanying colored photograph illustrates the overall appearance of the new Helleborus plant, showing the colors as true as it is reasonably possible to obtain in colored reproductions of this type. Colors in the photograph may differ slightly from the color values cited in the detailed botanical description which accurately describe the colors of the new Helleborus plant. The photograph comprises a side perspective view of a typical flowering plant of ‘BLT04’ grown in a ground bed.

DETAILED BOTANICAL DESCRIPTION

The aforementioned photograph and following observations, measurements and values describe plants grown in Aalsmeer, The Netherlands in containers during the winter in a glass-covered greenhouse and under conditions which closely approximate commercial Helleborus production. During the production of the plants, day temperatures ranged from 14° C. to 16° C. and night temperatures averaged 10° C. Plants had been growing for one year when the photograph and the description were taken. In the following description, color references are made to The Royal Horticultural Society Colour Chart, 1995 Edition, except where general terms of ordinary dictionary significance are used.

-   Botanical classification: Helleborus niger×Helleborus sternii     ‘BLT04’. -   Parentage:     -   -   Female, or seed, parent.— Helleborus niger ‘Louis Cobbet’,             not patented.         -   Male, or pollen, parent.—Proprietary selection of Helleborus             stemii, not patented. -   Propagation:

Type: By tissue culture.

-   -   -   Root description.—Medium in thickness, fleshy; whitish brown             in color.         -   Rooting habit.—Freely branching, moderately dense.

-   Plant description:     -   -   Plant form and growth habit.—Herbaceous perennial. Compact,             upright and mounded plant habit; strong and vigorous growth             habit.         -   Plant height.—About 30 cm.         -   Plant diameter (area of spread).—About 20 cm.

-   Foliage description:     -   -   Arrangement.—Palmately compound with five leaflets per leaf.         -   Leaf length.—About 10 cm to 15 cm.         -   Leaf width.—About 5 cm to 7 cm.         -   Leaflet shape.—Ovate.         -   Leaflet apex.—Acute.         -   Leaflet base.—Attenuate.         -   Leaflet margin.—Serrate.         -   Leaflet texture, upper and lower surfaces.—Smooth, glabrous.         -   Leaflet venation pattern.—Pinnate; reticulate.         -   Leaflet color.—Developing leaves, upper surface: Close to             139A. Developing leaves, lower surface: Close to 137C. Fully             developed leaves, upper surface: Close to 139A; venation,             close to 137D. Fully developed leaves, lower surface: Close             to 137C; venation, close to 184B.         -   Petiole.—Length: About 15 cm. Diameter: About 5 mm. Texture,             upper and lower surfaces: Smooth, glabrous. Color, upper and             lower surfaces: Close to 183A.

-   Flower description:     -   -   Flower arrangement and shape.—Single rotate flowers arranged             on cymes; flowers face outwardly to slightly nodding. Freely             flowering habit, about 10 to 15 flowers and flower buds per             inflorescence. Petals transformed into nectaries.         -   Fragrance.—None detected.         -   Natural flowering season.—Long flowering period; plants             flower from January through March in The Netherlands.         -   Flower longevity on the plant.—About one to two months;             flowers persistent.         -   Flower buds.—Length: About 3 cm. Diameter: About 1.7 cm.             Shape: Oblate. Color: Close to 185C.         -   Inflorescence size.—Length: About 20 cm. Diameter: About 20             cm.         -   Flowers.—Diameter: About 5 cm. Depth (height): About 2 cm.         -   Sepals.—Arrangement: Five in a single whorl. Length: About             4 cm. Width: About 3 cm. Shape: Roughly obovate. Apex:             Obtuse. Base: Obtuse. Margin: Slightly serrate. Texture,             upper and lower surfaces: Smooth, glabrous. Color: When             opening, upper and lower surfaces: Close to 186D. Fully             opened, upper and lower surfaces: Close to 186D.         -   Peduncles.—Strength: Strong. Length: About20 cm. Diameter:             About 3 mm. Aspect: About 90° from vertical. Texture:             Smooth, glabrous. Color: Close to 194A overlain with close             to 176B.         -   Reproductive organs.—Stamens: Quantity per flower: About 50.             Anther shape: Elliptical. Anther length: About 3 mm. Anther             color: Close to 154C. Pollen amount: None observed. Pistils:             Quantity per flower: About five. Pistil length: About 2 cm.             Stigma shape: Club-shaped. Stigma color: Close to 145C.             Style length: About 8 mm. Style color: Close to 145C. Ovary             color: Close to 145B. Nectaries: Arrangement: About 12             to 15. Length: About 1 cm. Diameter: About 3 mm. Color,             immature: Close to 141 C. Color, mature: Between 141C and             150A. Seeds/fruits: Seed and fruit development have not been             observed.

-   Garden performance: Plants of the new Helleborus have been observed     to have good garden performance and to tolerate rain, wind and     temperatures from about −10° C. to about 25° C.

-   Pathogen/pest resistance: Plants of the new Helleborus have been     observed to be relatively tolerant to Mildews. Plants of the new     Helleborus have not been shown to be resistant to pests and other     pathogens common to Helleborus. 

1. A new and distinct Helleborus plant named ‘BLT04’ as illustrated and described. 